(1) Field of the Invention
This invention relates to a method for producing trimethylhydroquinone from isophorone. The trimethylhydroquinone is a useful substance as an intermediate compound for preparing vitamin E.
(2) Prior Art
The following methods are mainly known for preparing trimethylhydroquinone.
In one of them, 2,3,6-trimethylphenol is sulfonated with sulfuric acid and it is then oxidized with manganese dioxide (Japanese Laid-Open Patent Publication No. 62-108835). This method is not desirable because a large quantity of heavy metal waste is produced, which have a large influence on environment. In addition, the 2,3,6-trimethylphenol as a starting material is expensive, so that the cost for the production of trimethylhydroquinone is high.
Another method relates to chloro-oxidation of 2,4,6-trimethylphenol (Japanese Patent Publication No. 5-68456). Because quite toxic chlorine is used as an oxidizing agent in this method, the process is dangerous to be worked. In addition, when organic chlorine compounds are generated as by-products, the cost for the disposal of waste is expensive.